The Effects of L: -theanine on Alpha-Band Oscillatory Brain Activity During a Visuo-Spatial Attention Task

Program in Cognitive Neuroscience and Schizophrenia, The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
Brain Topography (Impact Factor: 3.47). 06/2009; 22(1):44-51. DOI: 10.1007/s10548-008-0068-z
Source: PubMed


Background/Objectives Ingestion of the non-proteinic amino acid l-theanine (γ-glutamylethylamide) has been shown to influence oscillatory brain activity in the alpha band (8–14 Hz) in humans
during resting electroencephalographic (EEG) recordings and also during cognitive task performance. We have previously shown
that ingestion of a 250-mg dose of l-theanine significantly reduced tonic (background) alpha power during a demanding intersensory (auditory-visual) attentional cueing task. Further, cue-related
phasic changes in alpha power, indexing the shorter-term anticipatory biasing of attention between modalities, were stronger on
l-theanine compared to placebo. This form of cue-contingent phasic alpha activity is also known to index attentional biasing
within visual space. Specifically, when a relevant location is pre-cued, anticipatory alpha power increases contralateral
to the location to be ignored. Here we investigate whether the effects of l-theanine on tonic and phasic alpha activity, found previously during intersensory attentional deployment, occur also during
a visuospatial task. Subjects/Methods 168-channel EEG data were recorded from thirteen neurologically normal individuals while engaged in a highly demanding visuo-spatial
attention task. Participants underwent testing on two separate days, ingesting either a 250-mg colorless and tasteless solution
of l-theanine mixed with water, or a water-based solution placebo on each day in counterbalanced order. We compared the alpha-band
activity when subjects ingested l-Theanine vs. Placebo. Results We found a significant reduction in tonic alpha for the l-theanine treatment compared to placebo, which was accompanied by a shift in scalp topography, indicative of treatment-related
changes in the neural generators of oscillatory alpha activity. However, l-theanine did not measurably affect cue-related anticipatory alpha effects. Conclusions This pattern of results implies that l-theanine plays a more general role in attentional processing, facilitating longer-lasting processes responsible for sustaining
attention across the timeframe of a difficult task, rather than affecting specific moment-to-moment phasic deployment processes.

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    • "Detected amounts of GABA and theanine were 0.25 mg and 52 mg, respectively, in shaded white tea, while they were 0.15 mg and 17 mg in Sagara. Knowing that most human mood studies have used higher doses of theanine (for example, 200 mg in Juneja et al. [3] and Higashiyama et al. [23]; and 250 mg in Gomez-Ramirez et al. [24]), the low dose of 52 mg in shaded white tea in this study might have been insufficient. However, one previous study on the effect of theanine consumption on human brain alpha activity found significantly greater and increasing alpha activity after ingestion of 50 mg theanine compared with placebo [25]. "
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    ABSTRACT: Background Green tea has become renowned for its health benefits. In this study, we investigated the anti-stress effect of two kinds of green tea against a mental stress task load. Methods Warm water, ordinary green tea (Sagara), and shaded white tea, which contains more amino acid components than Sagara, were used as test samples in a randomized cross-over design study. Eighteen students (nine male and nine female) participated in three experimental trials on different days at intervals of seven days. Saliva was collected before beverage intake and after performing the mental stress load tasks. Concentration of chromogranin A (CgA) in the saliva was used as an index of autonomic nervous system activity. Results CgA level increased after the mental tasks, but intake of green tea inhibited this increase; the anti-stress effect was even greater after consumption of shaded white tea. Intake of shaded white tea also lowered Total Mood Disturbance (TMD) score on the Profile of Mood States (POMS); subjects in this condition tended to perform more calculations in the arithmetic task than those in the warm water treatment condition. Conclusions Salivary CgA concentration levels increased after mental stress load tasks, but ingestion of green tea inhibited this increase. This anti-stress effect was larger after the consumption of shaded white tea than after Sagara. Shaded white tea intake also lowered TMD score (POMS) and tended to improve performance on an arithmetic task compared to warm water, suggesting that shaded white tea might also improve mood during and after mental stress load.
    Journal of PHYSIOLOGICAL ANTHROPOLOGY 07/2014; 33(1):20. DOI:10.1186/1880-6805-33-20 · 1.27 Impact Factor
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    • "Recently, our group performed the first investigation of the role of alpha-band oscillations in visual feature-based selective attention (Snyder and Foxe, 2010). This study aimed to expand on prior research in selective attention which had shown that alpha-band power increases index the degree of attentional suppression in visuospatial attention tasks (Worden et al., 2000; Sauseng et al., 2005; Yamagishi et al., 2005; Kelly et al., 2006, 2009, 2010; Thut et al., 2006; Rihs et al., 2007; Gomez-Ramirez et al., 2009), intersensory attention tasks (Foxe et al., 1998; Fu et al., 2001; Gomez- Ramirez et al., 2007), sustained visual attention tasks (Dockree et al., 2007; O'Connell et al., 2009) and audiospatial attention tasks (Kerlin et al., 2010; Banerjee et al., in press). We asked if alpha-band mediated suppression would be observed in a feature-based selective attention task. "
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    Cortex 05/2011; 48(8):1035-42. DOI:10.1016/j.cortex.2011.05.003 · 5.13 Impact Factor
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    • "We probed anticipatory activity in lower-tier visual areas by measuring a broadband ERP component known as the LDAP (latedirecting attention positivity), defined by relatively positive amplitude contralateral to the direction of a central spatial cue (Harter et al., 1989; Hopf & Mangun, 2000), as well as lateralization of alpha-band (8–14 Hz) amplitude to the visual hemisphere ipsilateral to cue direction (Worden et al., 2000). Both the LDAP and alpha lateralization have been associated with the anticipatory modulation of excitability in early visual areas responsible for processing an upcoming target (Worden et al., 2000; Kelly et al., 2005, 2006, 2009; Talsma et al., 2005; Simpson et al., 2006; Thut et al., 2006; Gomez-Ramirez et al., 2009). In addition, we tested for effects on two other spatially selective (i.e. "
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